>>52032
I found something. Well nothing that outright say a deal had happened. But a situation where we could hypothesize a deal happening.
Here's this CNN article:
https://edition.cnn.com/2024/03/09/politics/us-prepared-rigorously-potential-russian-nuclear-strike-ukraine/index.html
It's basically an advertisement for that book, The Return of Great Powers. Available on libgen, and I got it too. While the book is longer, but in that particular topic it basically writes the same as the article - I've only skimmed it so I overlooked lotsa details - I search Kherson and rolled through the pages. What I can tell that it polishes the rod of the US govt. and tells us that Putin and Co. are stupid so the US won against an inferior opponent, very impressive.

The story in short:
Kharkov offensive was a huge setback for the Russians, and when the Kherson offensive started they started to panic. Their worries was twofold:
1. they were scared losing Kherson;
2. they were scared that their troops will be steamrolled by the Ukrainians;
So this would have been a great debacle for them, and they were seriously considering to use of tactical nuke if both happened. They started to circulate Ukraine dirty bomb story in case they have to cover up a nuclear strike.
But heroic US diplomacy and secret services were vigilant. So they and Sholz went to Modi and Xi Jinping, and bullied them into going to Putin and pressure him not to use the nukes.
World Saved again by timely and resolute US intervention.

Now.
We can speculate that yes losing lots troops, equipment and key city was actually uncomfortable, and the use of nukes are kinda sorta are always on table, so these offensives could have triggered the use of them. So they could make a deal that they make Ukraine halt and give time for an orderly retreat, and Russia don't use nukes.
This doesn't sound very convincing, but rounds out the story above and offers something to negotiate with.